Ejector punch



R. E. FELDBORG EJECTOR PUNCH July 16, 1968 Filed Dec. 20, 1965 36INVENTOR RICHARD E. FELDBORG United States Patent 3,392,614 EJECTORPUNCH Richard E. Feldborg, 16174 Rosemont Ave., Detroit, Mich. 48219Filed Dec. 20, 1965, Ser. No. 514,921 7 Claims. (Cl. 83-128) ABSTRACT OFTHE DISCLOSURE A piercing punch assembly having a pin for ejecting thecut blank from the end of the punch. The assembly includes a pluralityof balls carried within the punch and which when the punch is invertedand the pin retracted Will lock the pin member in the retracted positionto permit the end of the punch and the pin to be reground.

. The present invention relates to piercing punch assemblies,particularly to such an assembly having means for ejecting the cutblanks or slugs which have the tendency to adhere to the punch assemblyand more particularly to a new means for maintaining the ejector pin ina retracted position while the working face of the punch and the pin arebeing ground.

Piercing punch assemblies have been heretofore provided which include aspring actuated pin for ejecting the blank from the end of the punch asthe punch is being retracted from the work material. These have alsosometimes included means for maintaining the ejector pin in a retractedposition with the working surface thereof coplanar with the workingsurface of the punch so that these surfaces can be ground at the sametime and without altering the relative positions of these surfaces inthe working positions.

One such assembly is disclosed in US. Patent No. 2,- 917,960 issued Dec.22, 1959, to Robert A. Gargrave. The assembly therein disclosedcomprises a headed pin member carried within an axial bore provided inthe punch and being spring urged toward a position in which a portion ofthe pin member extends axially from the working surface of the punch.The spring is relatively light so that it will yield when the end of thepin contacts the surface of the work material. The pin remains in theretracted position until the punch is retracted from the work materialand as the punch is being retracted, the force on the end of the pin isreduced sulficiently to permit the spring to move the pin to an extendedposition to thereby dislodge the blank from the end of the punch.

\ The assembly further includes means in the form of a cotter pinadapted to be engaged beneath the head of the ejector pin formaintaining the pin in a retracted position with the working surfaces ofthe punch and pin coplanar so that these surfaces can be ground and whenthe grinding operation is completed, the pin when again extended willassume a position in which the working surface thereof is the samedistance from the working surface of the punch as it was before thegrinding was undertaken.

While pierce punch assemblies like those disclosed in the aforementionedpatent have been suitable for their intended purpose, they are generallyquite expensive because of the mechanism required for actuating theejector pin and also by reason of the particular mechanism utilized formaintaining the ejector pin in a retracted position for grinding.Further, a large part of the retracting mechanism extends exteriorly ofthe punch and this limits the number of such punches which can beprovided in a given space and interferes with retraction of the ejectorpins where a large number of punches are provided within relativelyclose proximity. Further, the cotter pins can dislodge from the punchesduring the grinding operation ice which may result in damage to theworking surface of the pin.

The present invention overcomes these difliculties by providing apiercing punch assembly in which means disposed entirely within thepunch are provided for selectively maintaining the ejector pin in aretracted position. Thus a large number of punches can be providedwithin a given area. Once in the retracted position there is littledanger of the pin accidentally disengaging and thereby assuming theextended position during grinding. The particular retaining means aswell as the ejector pin assembly can be produced much more economicallythan heretofore possible so that the cost of producing piercing pinassemblies is substantially reduced by the construction of the presentinvention.

It is an object then .of the present invention to reduce the cost ofpiercing punch assemblies by providing a more economically producedejector pin mechanism for such assemblies.

It is another object of the present invention to facilitate the grindingof the work surfaces of a piercing punch and the ejector pin for suchpunches by providing a new means for maintaining the ejector pin in aretracted position during the grinding operation.

It is still another object of the present invention to increase thenumber of piercing punch assemblies .of the type having means forretaining the ejector pin in a retracted position, which can be providedin a given area by positioning such means entirely within the piercingpunch.

Still further objects and advantages of the present invention willreadily occur to one skilled in the art to which the invention pertainsupon reference to the following description. The description makesreference to the following drawings in which like reference charactersrefer to like parts throughout the several views and in which:

FIG. 1 is a longitudinal cross sectional view partly diagrammaticillustrating one preferred piercing punch assembly of the presentinvention in use,

FIG. 2 is a fragmentary cross sectional view of a portion of thestructure shown in FIG. 1 enlarged somewhat for purposes of clarity andillustrating the ejector pin in the position assumed as the workingsurface of the punch strikes the work material.

FIG. 3 is a fragmentary cross sectional view similar to FIG. 2 butillustrating the operation of retraction retaining mechanism of thepresent invention and illustrating the piercing punch assembly in aninverted position to permit the work surfaces thereof to be ground forsharpening, and

FIG. 4 is a cross sectional view similar to FIG. 2 but illustratinganother preferred embodiment of the present invention.

Now referring to the drawings for a more detailed description of thepresent invent-ion, one preferred embodiment is illustrated in FIGS. 1-3as comprising a punch member generally indicated at 10 carried by aholder comprising a punch shoe 12 and a punch retainer 14 secured one tothe other in any convenient manner such as by screws or dowels (notshown). A die retainer 16 is spaced from and parallel to the punchretainer 14 and carries a die shoe 18 on the side opposite the punchretainer 14. A stripper member 20 is disposed intermediate and inparallel relationship with the punch retainer 14 and the die retainer16. The die retainer 16 and the die shoe 18 carry a die button 22 in aposition to axially receive the end of the punch member 10 as willbecome more apparent as the description proceeds. The stripper member 20is provided with 'an opening 24 for permitting movement of the end ofthe punch member 10 into the die button 22. The stock or work material26 to be cut is disposed intermediate the stripper memportion 30 so thatwhen the punch shoe and the punch retainer 14 are. secured together, thepunch member is locked in position. Such a means of retaining the punchmember 10 in position is referred to as a head type or shoulder punchassembly. It will be apparent that other means for retaining the punchassembly can be 'used as well and such assembly could be a conventionalball lock type assembly rather than the assembly illustrated.

The barrel 32 of the punch member 10 extends from the bore 28 andterminates in a reduced diameter nose portion 36. The nose portion 36 isaxially aligned with the'opening 24 in the stripper member and with theinterior-of the die button 22. As can best be seen in FIGS. 2-3, the endof the nose 36 is formed with a planar work surface 38 which is normalto the axis of the punch member 10.

Also as can best be seen in FIGS. 2-3, the punch member 10 is providedwith an axial through bore 40.

The punch member 10 is counterbored axially from the upper end to forman enlarged portion 42 of the bore 40 and then counterbored again fromthe upper end to form a portion 44 of a diameter intermediate thediameters of the through bore 40 and the enlarged portion 42. Thejuncture of the portions 42 and 44 is formed by an upwardly inclinedshoulder 46 and the juncture between the bore 40 and the portion 42 isformed by a similarly inclined shoulder 48.

An ejector pin 50 is carried in the through bore 40 and comprises anelongated member having a straight portion 52 adapted to be axiallyreceived in the bore 40 and an integrally joined spring portion 54carried in the enlarged portion 42. A screw stud 56 (FIG. 1) received inthe upper end of the enlarged portion 42 retains the ejector pin 50 inplace and provides a seat for the free end of the spring portion 54.

A cup member 58 is staked or otherwise fixed to the straight portion 52of the pin 50 and includes a frusto conical side wall 60 for receivingthe spring portion 52 and a cylindrical portion 62 through which thestraight portion 52 extends. The side wall 60 is substantiallyconcentric to the shoulder 46 and the upper edge of the wall 60 extendsclosely adjacent the inner Wall forming the enlarged bore 42 so that thewall 60 and the shoulder 46 coact to limit the extension of the ejectorpin 50. The spring portion 54 bears against the cup member 58 to urgethe pin 50 toward the extended position shown in FIG. 1 and in which aportion of the pin 50 extends from the end of the nose portion 36 of thepunch member 10. A plurality, preferably three, of balls 64 are looselycarried in the bore portion 44.

In operation, the punch assembly is normally in the position illustratedin FIG. 1. The stock material 26 is fed across the die retainer 16 whilethe separate assemblies 12-14 and 1618 reciprocate relatively to oneanother. During such motion, the nose portion 36 of the punch member 10passes through the opening 24 in the stripper plate 20 and pushesthrough the work material 26 and into the die button 22 to cut a blankfrom the material 26. The blank will normally drop downwardly throughthe die button 22 and fall through an opening 66 provided in the dieshoe 18.

The stripper member 20 will prevent the cut blank from following thepunch member 10 as it is retracted but without more, the blank sometimesmight adhere to the work material 26 as the punch member 10 iswithdrawn. The ejector pin 50 obviates this. The spring portion 54 isrelatively light so that as the working surface 38 of the punch member10 comes intocontact with the surface of the work material 26, theejector pin 50. will be moved to the retracted position shown in FIG. 2so that it will produce no interference with the cutting action producedby the punch member 10. When the cut is made,-the force-is released.from the end of the ejector pin 50 and the spring .portion 54 moves thepin 50 to the extended position illustrated in. FIG, .1. This causes theend :of the pin 50 to bear fagainsttthe cut blank and to push.itdownwardly through the die button 22 and the opening 66. I .7 It isapparent that the work surface 38 of the punch member 10 must beperiodically ground oif to maintain the surface planar and the edgessharp. Further, that without some means ofmaintaining the ejector pin 50in aretracted position duringwthis operation the end of the. pin 50would interfere with-the grinding and sharpening-Also, since. ratherclose tolerances must be kept betweenthe work surface 38 and the end ofthe pin 50 when the pin 50 is extended and also because the end surfaceof thepin 50 also forms a part of the work surface 38, it is, desirableto retract the pin 50 to a position in which the end surface of the pin50 is substantially co-planar with the work surface 38 during grinding.

To grind the Work surface 38 and the end surface of the pin 50 then thepunch assembly is first inverted to the position shown in FIG. 3. Thepin 50 is then pushed to a position in which the end surface isbelow-the work surface 38 by any suitable tool (not shown). This permitsthe ball'members 64 to fall to a position intermediate the wall 60 ofthe cup member 58 and the shoulder 46. The diameter of the "balls 64 andthe angle of inclination of the Wall portion 60 and the shoulder 46 issuch that with the balls 64 in this positionthe pin 50 is maintained ina retracted position in which the end surface of the pin50 issubstantially planar with the work surface 38.'The free edge of the wall60 is spaced suificiently close to the wall defining the bore portion 42to prevent the ball members 64 from falling'past the cup member 58 andthe cylindrical portion 62 of the cup member 58 is spaced suflicientlyclose to the wall defining the boreportion 44 to -prevent the ballmembers 64 from working themselves pastthe cup member 58 and into thebore portion 44, before grinding.

The surface 38 and the end surface of the pin 50 then can be groundwithout the danger of the pin 50 accidentally moving'to the extendedposition. After the grinding has been accomplished, the assembly isagainireturned to its operating position and the pin 50 is pushed intothe punch member 10 to permit the balls 64 to fall past the cylindricalportion 62 of the cup member 48 and to return to the bore portion 44 outof the way of the operation of the pin 50. After re-grinding, the endsurface of the pin member 40 and the work surface 38, these surfaceswill be spaced the same distances in the extended position as they werebefore grinding.

FIG. 4 illustrates a punch assembly similar to the one described but inwhich a pin 152 is formed integrally with a cup 158 similar to thestraight portion 52 and cup 58 of the assembly of FIGS. 1-3. A spring154 is separate from the cup member 158 and pin 152 and urges the pin152 toward the extended position but is otherwise substantially asdescribed for the modification of FIGS. 1-3.

It is apparent that a punch assembly has been described in whichretraction of the ejector pin for resurfacing has been greatlyfacilitated over previous means for performing this function. Theparticular retaining mechanism is relatively inexpensive and since it islocated entirely within the punch member 10, it in no way interfereswith the placement and positioning of the punch members in an assembly.

It is also apparent that although I have described but two embodimentsof my invention, many changes and modifications can be made thereinwithout departing from the spirit of the invention as expressed by theappended claims.

I claim: 1. A piercing punch member comprising,

(c) spring means carried in said bore and urging said pin member towardan extended position in which the 6 end of said pin member extends fromthe end of said body portion, (d)"means disposed within said bore andselectively operable to retain said pin member in a retracted (a) a bodyportion having a longitudinal bore, 5 position in which the end of saidpin member is sub- (b) a pin member axially slidably mounted in saidbore, 'stantially coplanar with the end of said body portion, (c) springmeans carried in said bore and urging said (e) said last mentioned meanscomprising a counterpin member toward an extended position in which thebore in said body portion to form an enlarged porend of said pin memberextends from the end of said tion of said bore; a second counterbore insaid body body portion, 10 portion to form a second enlarged portionadjacent :(dz) 1, means disposed within said bore and selectively to andof a smaller diameter than said first enlarged operable to retain saidpin member in a retracted portion; a frusto-conical shoulder formed insaid position in which the end of said pin member is subbody portion atthe junction of said enlarged porstantially coplanar with the end ofsaid body portion, tions; a cup member secured to said pin member and(e) said last mentioned means comprising a frustocarried within saidenlarged bore portions and havconical shoulder portion formed in saidbore, a ing a. frusto-conical sidewall engaging with said frusto-conicalmember carried by said pin member shoulder to limit extended movement ofsaid pin and adapted to be urged against said shoulder portion member;said cup member further having a cylinby said spring means to limitoutward extension of drical portion adapted to be received in saidsecond said pin member, and a plurality of balls carried enlargedportion;aplurality of ball members normalwithin said bore and adapted tobe wedged interly positioned in said second enlarged portion andnormediate said shoulder portion and said frusto-conical mally retainedtherein by said cylindrical portion of member to retain said pin memberin said retracted said cup member; and said ball members beingselecposition. tively. movable from said second enlarged portion to 2. Apiercing punch member comprising, a position intermediate said sidewallof said cup mem- (a) a body portion having a longitudinal bore, ber andsaid shoulder to retain said pin member in a (b) a pin member axiallyslidably mounted in said retracted position.

bore, 5. The piercing punch as defined in claim 4 and in (0) springmeans carried in said bore and urging said which said spring meanscomprises a spring member pin member toward an extended position inwhich carried in said first enlarged portion and having one end the endof said pin member extends from the end of seated in said cup member.said body portion, 6. The piercing punch as defined in claim 5 and in((1) means disposed entirely within said bore and selecwhich said springmember is integrally formed with said tively operable to retain said pinmember in a repin member. tracted position in which the end of said pinmem 7. A piercing punch member comprising, ber is substantially coplanarwith the end of said (a) a body portion having a longitudinal bore, bodyportion, (b) a pin member axially slidably mounted in said bore (e) saidspring means comprising a cup member and spring means carried in saidbore urging said pin carried by said pin member, and a spring portionmember toward an extended position in which the integrally formed at theinner end of said pin memend of said pin member extends from the end ofsaid ber and received by said cup member. body portion, and 3. Apiercing punch member comprising, (6) means disposed entirely withinsaid bore and (a) a body portion having a longitudinal bore, operableupon said body portion being inverted to a (b) a pin member axiallyslidably mounted in said position in which said pin member extendsupwardly bore, from said body portion and upon the end of said pin (0)spring means carried in said bore and urging said member being movedinwardly into said bore to lock pin member toward an extended positionin which said pin member in a retracted position in which the the end ofsaid pin member extends from the end of end of said pin member issubstantally coplanar with said body portion, the end of said bodyportion, and (d) means disposed entirely within bore and selec- (d) saidlast mentioned means including a plurality of tively operable to retainsaid pin member in a remembers loosely carried within said body portiontracted position in which the end of said pin memand movable to aposition intermediate said pin member is substantially coplanar with theend of said body ber and said body portion upon inverting said bodyportion, portion and retracting said pin member to thereby (e) saidspring means comprising a cup member carried lock said pin member in theretracted position.

'at the inner end of said pin member, and a spring member carried insaid bore and having one end References Cited seated in said cup memberto urge said cup member and said pin member to an extended position.UNITED STATES PATENTS 4. A piercing punch member comprising, 2,917,96012/ 1959 Gargrave 83-128 (a) a body portion having a longitudinal bore,3,106,120 10/ 1963 Reece 83-128 (b) a pin member axially slidablymounted in said 3,222,963 12 19 5 Larson bore, 3,255,654 6/1966 Bleicher83-128 5 WILLIAM S. LAWSON, Primary Examiner.

